triangle budgets for roblox: how much is too much?
roblox is a mobile platform that happens to run on pcs. more than half of most games' players are on a phone, and a phone does not care how good the piece looked in the render. the budget is the part of the brief that decides whether the asset ships or gets rebuilt.
three budgets, not one
- triangles: how much geometry the gpu draws. the number people quote, and the least important of the three on its own.
- textures: how many maps at what size. texture memory is what actually crashes low-end phones.
- draw calls: how many separate materials and meshes. ten props sharing one atlas cost far less than ten props with ten materials, at the same triangle count.
what the engine will and will not take
a single meshpart has a hard triangle cap on import; go over it and studio refuses the file. the exact number has moved over the years, so check the creator docs, and treat it as a ceiling rather than a target. a piece near the cap is a hero piece, not a prop.
textures are limited in size per map, and the engine downsamples on weaker devices anyway. a 1024 atlas is the everyday size; 2048 is for something the camera gets close to; 4096 is almost never the right answer on roblox.
budgets that ship
these are the bands bevel briefs against for a game that has to run on phones. a pc-only experience can double them; a game with hundreds of instances of the same prop should halve them.
| asset | a sensible band |
|---|---|
| small prop, tool, pickup | 200 to 1,500 triangles, one 512 or 1024 atlas shared with its pack |
| weapon (first-person visible) | 2,000 to 6,000 triangles, one 1024 atlas, pbr optional |
| character (r15, playable) | 6,000 to 15,000 triangles across parts, one or two 1024 atlases |
| modular environment kit piece | 300 to 2,000 triangles each, the whole kit on one or two atlases |
| hero set piece (a statue, a boss) | up to the engine cap, split across parts, its own texture set |
the line to put in the brief
under 4k triangles, one 1024 atlas, collision included, must run on mobile.
that one line is a spec a modeller can hit first time. "optimised" is not; every modeller has a different idea of it. a number is a contract.
lods, collision and the things after the model
- collision: a separate, simple mesh or a decomposition setting. a hero mesh used as its own collision is the most common performance mistake on the platform.
- level of detail: roblox generates lods for meshparts automatically in many cases; a piece with clean topology degrades gracefully, a mess does not.
- streaming: environments should be built as kits so the engine can stream them in and out. one giant mesh streams as one giant mesh.